FUEL BACKFLOW VALVE TEST
THIS WORK PACKAGE COVERS:
General mechanic's tool kit (item 121, WP 0176)
Track Vehicle Repairer (1) 63H10
Expendable and Durable Items:
Engine removed from vehicle and placed on a
flat stationary surface
Container for fuel, minimum one gallon capacity
The fuel backflow valve is a dual purpose valve.
It incorporates a check valve that prevents pressurized fuel generated by the purge pump
(wobble pump) from back flowing into the primary fuel filter.
It incorporates a by-pass valve that limits the fuel pressure to the manifold heaters.
The most notable symptom produced by a non-functioning backflow valve is a non-
functioning manifold heater. To determine if your backflow valve is functioning properly,
perform the following test.
1. Check free flow of valve (1).
a. Disconnect hose (2) [fuel out of valve] from outlet fitting (3).
b. Provide a suitable container to catch fuel.
c. Provide 0.5 psi at valve inlet fitting (4).
d. Fuel must flow freely at 0.5 psi from outlet fitting (3).
WP 0046 00-1